I hate to say it but think that has had a head strike and physically scratched the surface of your Y and M printheads. It’s definitely worth doing some rigorous cleaning on them first but I have a strange feeling they will need replacing. Unfortunately, the K head doesn’t look particularly good either, you must be having to print very slowly to output anything half decent.
My suggestion, speak to a local engineer or supplier and pay for someone to work their magic on it. Otherwise, buy some cleaning solution (preferably from the same supplier of your inks) and some clean wands and give the whole thing a damn good going over. Maybe even replace that K cap top. You could try manually flushing the heads with a syringe too if you’re feeling brave. However, do so at your own risk.
Best of luck
Stafford